In a heavy bottomed medium-sized pan (cast iron works great for these), heat four tablespoons of olive oil on high. Once the oil is hot, carefully slide in all the Brussels sprouts. Toss them to coat them in the olive oil, season with some sea salt, and let them cook for a minute or two. Give them a stir and continue cooking until they get golden and seared in places, about 5-7 minutes. If the pan seems too dry while they are cooking, add a little more olive oil.
Once they are crispy and golden brown in places, remove the Brussels sprouts from the pan and place them in a medium mixing bowl. Squeeze the juice from half a lemon all over them. Sprinkle in half the chives and half the pine nuts. Start adding the aged balsamic vinegar, drizzling it back and forth across the Brussels sprouts. Stir it all together with a spoon. Taste. Season with more sea salt, some black pepper, and more aged balsamic until the taste is to your liking. Add the remaining chives and pine nuts, give it all one final stir, and serve.